Infinitely variable gear



Sept. 2, 1952 w. ZWICK INFINITELY VARIABLE GEAR Filed Feb. 3, 1949 3Sheets-Sheet 1 Ii 521-25 w li F) TTORNEY Sept. 2, 1952 w. ZWlCKINFINITELY VARIABLE GEAR 3 Sheets-Sheet 2 Filed Feb. 5, 1949 Sept. 2,1952 w, zw c INFINITELY VARIABLE GEAR 5 Sheets-Sheet 3 Filed Feb. 3,1949 dicate corresponding parts in each figure.

Patented Sept. 2, 1 952 :Walter ZwickgHuemoz sur Ollon, SwitzerlandApplication'February 3, 1949, Serial No. 74,319

- In Switzerland December-'24, 1948 This invention relates to infinitelyvariable or continuous gears. Such gears are an urgent requirement foruse in. machine tools andother purposes, especially for use in vehicles.

It is; an object of my invention to provide an infinitely variable gearthe torque of which is automatically accommodated'to the load torque, i.e. to the tr'active resistance in the case of vehicles, for instance. v

Another object is to provide a gear which is characterised in thatrocking. members are hinged at eccentrically arranged centers and rtateat the speed ofa shaft whilst, on the one. side,'they are connected tothe crank of another shaft by means of a link means, and'on the otherside, they act on a wheel of a locking mechanism by means of a rack orany other suit,- able coupling means.

A further object is to link centrifugal weights to the rocking membersand to link a rack or another suitable coupling means to centersconnected with the centrifugal weights.

A still further object of my invention is to increasethe oscillation.transmitted to the wheel ofthelocking mechanism by means of a rack oranother coupling means by the insertion of a transmission gear.

Other objects and features will be apparent as the following descriptionproceeds, reference being had to theJaccompanying drawings, illustratingdifferent embodiments of my invention ina schematic manner, and wherein:Fig. 1 is a cross sectional side view of a first example, e .Fig. .2 isa front view of the example shown in Fig. 1, with different parts insection,

' Fig. 3 is an axial section through a second embodiment, V

' Fig; 4 is a section along the line 4--4 of Fig. 3, "Fig. 5 is asection along the line 5-5 of Fig. 3, Fig. 6 is the same section'as Fig.5, but in another position 'of the several parts,- i

Fig.- 7 is an axial section of a third embodimerit,

Fig. 8 is a section along the line: 8--8 of Fig- '7, Fig. 9 is a sectionalong the line 9- 9 of Fig. 7, -Fig. 10 is a section along the line 10of Fig. '1, and

Fig. 11 illustrates afourth example. I In the drawings like referencecharacter in- In the followingdescriptionspeed means always the numberof revolutions perv unit of time. meanin now to Figs; 1 and 2, a cage scomph singthreedi'sks s1, s2, s3 rigidly connected to 11 Claims. (Cl.,74-114) 2 one another by bolts m'is fixed to a drive shafttdi by meansof the pin M to-rotate at the same speed as ,the latter. A double-armedrockingde vr c--c' is fixed to a member 0 journalled the. disks 8;, s2,.93. A driven shaft 1) coaxial to the drive shaft a comprises a crank 70and a returnv crank k1 The ends of shaft a and crank 70. are shown inFig. 2 by two vertical heavy lines at the left of the dotted verticallines defining ljcin.v M. The arm 0 of the rocking lever c--c isconnected with the crank k by means of a link d. Letus assume that thecage 8 rotates while thecrank'lc is, at rest, then the lever cc'oscillates. s--k-d-c in Fig. 1 is an articulated quadrangle or anoscillating crank, t

A frame eg--h is linked to the end of the arm vc of the lever cc', thisframe carrying a centrifugal weight I and having a rack a linked to it.The common point of application of the centrifugal forces F applied toe,f, g, h and z is designated by f. The 'force F acts always in radialoutward direction with regard to the .axis of rotation of the shafts aand '22.. The rack 22 meshes witha gear wheel 12 loosely and rotate ablymounted on a fixedbearing p. The rack; is heldin correct position withrespectto wheel 2' by means of guides 15, h as shown inFigs. 5 and 6.Thiswheel 2' forms a part of acoaster brake.

n locking on counterclockwise rotation. On the crank 70 being stillassumed to be at rest and the frame e-g-h being moved by the oscillatingcrank s-,k -d--c in counterclockwise direction as seen from right toleft in Fig. 2, the rack 2 tries to rotate the gear wheel 1 in thecounter! clockwise direction relative to the cage .9. In an absolutesense the wheel 2' comes to rest if the counterclockwise rotationimparted bythe crank through the rack a is equal to the clockwise. r0;tation imparted by the cage 8. In thisfcas'e, the wheel 1' is also at'rest with regard to the fixed bearing p on which it is journalled. Ifthe counterclockwise rotation of the wheel 2', im: parted by the cranktends to further increase, this is prevented by the coaster brake 11.con-.- sisting'of the wheel 1' and the rollers 3 engaging the bearing p.Therefore, either the frame c-gh gives way whereby the centrifugalweight 1 approachesthe shaft a while offering considerable resistance tothis displacement, or the crank It gives way and moves in clockwisedirection. In most cases both phenomena, i. e. giving way of the frameegh and rotation-of the crank it will occur simultaneously flhe anglethrough which the crank is will -berotated,

that is, the distance by which the centrifugal weight I will bedisplaced depends on the load torque to be overcome at the crank k onthe one hand, and on the speed of the drive shaft (1 on the other hand,in that this speed determines the resistance which the centrifugalweight 1' Will offer to a change in position.

Instead of a coaster brake any other suitable locking mechanism or brakemay be used.

If the crank 1c rotates, the wheel 2' gets through the rack z and'thelever cc' an oscillation from the uniformly rotating shaft a by theintermediary of the parts s, c, e, g, h, z and an oscillatory movementfrom the crank through the parts 11, c, c, e, g, h, a. The direction ofthe oscillation caused by the rotation of shaft a is either clockwise orcounterclockwise. with regardv to. cage 8, so that the wheel 2' isalternatelyretarded or accelerated with regard to the cage 5, the speedof wheel 1' decreasing and increasing with regard to cage s inaccordance with the wellkinematics of thecrank gear.- If theangular'velocity-imparted' to the wheels by the crankIc;in;counterclockwise direction is equal to the angularvelocityreceived from the-cage s in the clockwise direction, thewheel i is atrest in the absolute sense. A further increase of the angular velocityof the wheeliin counterclockwisedirection by the crank k, by which thisvelocity would become negative, is prevented bygthe. coaster brake (i,r, p). the structural. dimensions chosen (e. g.: c' c, smalldiameter ofwheel 1) result-in a limitation of'the'speedofjthe crank k-up to whichthe coaster=-brake locks and exerts a; torque. In theexample of Fig. 1this limiting speed amounts to slightly more than ,halfthe drivingspeed.

If the centrifugal weight f'is forced by the driven crank ktowards theaxis ofrotation of the shafts a and b,,it must be done against theconstraint of thejcentrifugal force F and against a. second force,namely the one necessary for decreasing the kinetic energy of thecentrifugal force from a; maximumvalue to a minimum value; according tothe greatest and the smallest amplitudes of this centrifugal weight.This force,increaseswithincreasing driving speed and with decreasingdriven speed, so-that itis dependent on the. relative speed" between thedriving and driven shafts. This second force doesnotyexertany-eifectonthe driven crank Io because on the centrifugalweights being forced inwardly, it; is added" to, the centrifugal force,while on theopposite, movement of the centrifugal' weights itis-subtracted from the centrifugal. force, so that with respect to acomplete period-thereisno effect-of this energy-changing force upon thedriven shaft provided that the driven speed isalmost as great as thedriving speed. However, the conditions will be altered assoon as thecoaster-brake locks owing to a smaller driven speed. Now, the coasterbrake, that is, a stationary machine part exerts the force necessary forpressing the centrifugal weights backwards, and an exactlycorresponding; force. is given to the crank 7c in additionto the forceapplied through the partsa s--c-- d-k- (Fig; 1). This force pressing thecentrifugalweightsinwards dependsboth-on the driving-speeddeterminingthe energy'oi the centrifugal weights, andon the differenceof the: driven speedfrom the driving speed. If the driven shaftrot'atesslowly, the change in the position of thecentrifugalweights must'beobtained in a shorter-"time than'if its speedapproachesthe drivingspeed.When the shafts rotates very This fact and also 4 rapidly and the crankk is almost at rest, this force may have considerable magnitude.

Therefore, a vehicle will be accelerated very quickly if the drive shaftrotates at a high speed. The great torque on the driven shaft resultsfrom the power on the rapidly rotating drive shaft. A reaction torqueoccurs on the coaster brake. The coaster brake lockswithout shocks forthereason that, on. the-one hand, it couples parts the absolute speedof'which is nil, and, on the other hand, the force exerted by thecoaster brake does not occur until the latter has locked. Itdoesnotexist before that moment.

The above-mentioned arrangement will now be multiplied in order toobtain balancing of forces andmasses; and a substantially uniformtorque. Referring to Fig. 1, a similar arrangement as above-described isreversed through It has a centrifugal weight f1 fixed to a rod orjournalled in the disks s1, s2, s3 and a rocking lever c1-c1' and acts.on the. return crank k1. It comprlses a rack 21 meshing with the'wheeli; By this second-arrangement. a. complete 10313316:- ing offorcesand masses is-obtained becausethe twoweights f and ii and, alltransmission parts are always in: symmetrical position with regard tothe axis of the shafts a. and .b, so thatzonly a pure couple of'forcesoccurs. Besides this, other rocking levers 02-02 and C3C3 coaxial tolevers 0-0 and c1-c1 respectively'and fixed to sleevesoz; oarespectively journalledon the rods 0 and 01, respectively are oscillatedby the crank drive k and In. With regard to the direction of rotation ofthe cage 8 (clockwise direction).- the parts 02 and'cs liebehind theline 001, and the parts 0 andc'i, in front of thisline. c2.c2." is asingle-armed lever pivotedas at o.inopposition to the double-armed leverc--c'. Therefore, when the parts c' and cflare-rocking. outwardly, theparts 02 and c3 'arepressed'inwardly. Whilst, during half a revolutionof. the crank k theparts 0' and ci'drive the wheel 1. incounterclockwise direction relatively to the cage s, the partscz and03', during the other half of the revolution, drive another gear wheel Zin counterclockwise direction, likewise loosely mounted on the bearingp, by means of therack e2 andza engaging the wheel Z. This adds to thesmoothing of the torque. The gear wheel 1 forms a part of a coasterbrake comprising rollers 3 engaging the bearing 2. This brake, too,admits only a rotation in clockwise direction.

There may be provided more than two axes of rotation for the rockinglevers without that more than one pair of cranks k, In, becomesnecessary.

Referring now to Figs. 3' to 6, the cage is formed of three discs s1, s2and s3, all connected with thedrive shaft 11.. They are interconnectedby bolts m (Fig. 4) to form a. rigid cage On which the shafts o, 01, 04and 05 aremounted (Fig. 4). Fig. 4 shows a multiple-oscillating crank.The arm 0 is fixed'to the shaft 0, arm-ca to the hollow shaft 02 etc.The hollow shafts 02, 03, 0e and 01 are shorter at both ends than therespective solid shafts o, o1, 04 and 05 traversing them. In Fig. 5 onlyone pair of rocking arms carrying the centrifugal weights is shown,viz.: c and or driving the common gear-wheel i'of the coaster? brake nby means of 'the'racks' z and. a1. The-coaster brake allows-the wheel Zto rotate-inclockwisc direction on the stationary bearing. bush, 11whilst it looks the wheel]v in counterclockwise direction. The racks. zand; 21 are formed-gas double racks (Figs, 3). The remaining;centrifacoas'nl s hts" n t, sho n u wa a d i iisi. rm 'n r -fin' 'Fig.1:'.' s; he. n;- trifuga'l weights connected-to the rocking levers c 2and cs act on asingle, loosely rotatable gear wheel;v (Fig. 3)1by-th eintermediary of the hollowf'shafts Q02 and-" and two doubleracks.

Loosely rotatable gear wheels g andr- (Fig.5) are movedin' acorresponding manner by the other rocking levers, and centrifugalweights. Fig, 6 r'epresentsthe arms 0 and 01" in their position nearestto the axis of rotation of r the 'shaftsa and b.) j The racks z and Z1are guidedinguides t and ti guaranteeing correct .positionyofthe rackswith regard'to the gear wheel-i. The guides tyand ii are provided on aguide member u rotatably mounted on, the bushp or on-the wheeli. Theguide member-u enables the racks to rotate about the axis of rotation ofthe shaft a; either together with the \vheeli or, by rolling on thewheel 2'.

Figs. '7 to 10 illustrate a further embodiment of rnyinvention; Theoscillatingcranks (Fig. 9) are not combined two and two on hollowshafts, but the centres of rotationlie close-t0 each other, such' as 0'and oflfor instance.- The rocking levers carrying the'centrifugalweights do not move racks as before,- but links'v, vi (Fig. 8) the otherends of which are 'eccentrically hinged to a toothedwheel w. Therefore,the wheel w receives an oscillating rotation derived from the crankdrive. This oscillation is transmittedto a toothed wheel- 2 mounted'on ashaft A supported on the cage '81 a rigidly connected-with the driveshaft itXFigE Theshaft'A carries a; toothed wheel 1! which-isin r'neshwith the central tootl ied wheel B. This latter is loosely mounted onthe'be'aring bush 'p and'constitutes-a partof the coaster braken-(Fig.--l 0) locking in the counterclockwise direction andadmittingrotation in the clockwise direction. The'ratio of 'transmission ischosen so i that the oscillatorymov'ement'is increased. In this way,the'absolute angular VOlOCity of the wheel B of the coaster brake willbe sooner nil than in the above example, i. e., the coaster brake willlook through a larger angleof themovement of the crank i so thatthe-latter will beidriven through this greater angle and the range ofthe ill infinitelyvariable 'torquewill be increased, be-

cause it is in the coaster brake where the reaction torque occurs, towhich the torque applied to the crank is opposite but of equalmagnitude. The coaster brakealso looks at higher speeds of the crank,although the angle through which the brake gives a torque, decreaseswith increasing speed of the crank.,- Therefore a larger range oftransmission between the driving and the driven shaftsis obtained, theextension of which may be'cho'sen at will by a suitable choice of thedianieters of the wheels 10, 0:, y'and B. Finally, this arrangementpermits giving thestationarybush 15 arid the coaster brakesuitablediameters without risk-ing large dimensions of the rocking levers andthe racks. The, arrangement-of Figs. '7 to 10 favors a compact design.The shafts 02 and 0a areshorter at their right ends than the shafts oand 01 in order to leave free way to the rocking levers of the shafts oand 01. The shafts 0 2 and 03 work upon a toothed wheel D (Fig. 7)similar to the toothed wheel W. The wheel D acts upon a brake wheel F bymeans of gear wheels E, A, Y lying diametrically opposite to X, A, Y forthe sake of mass balancing (Figs. 7, 8 and 10).

The disc $2 of the cage is directly fixed to the drive shaft a andcarries a bearing G (Fig. 7) for the crankshaft b. The disc .91 turnsloosely on the elastic coupling.

stationary bearing bush p, and the disc saloqsel'y on the stationarybearing bushI-I"(Fig. 7) 15 f Since one of the-two centrifugal w'eightslinked to a shaft (0, for instance) always swings out wardly when theother'moves inwardly "(FigsJ'S and 6), the centrifugal forces with theirforced fluctuations are already counterbalanced on: the shaft or axle 0.Therefore, great forces neither reach the drive shaft a nor the drivenshaft b. There are no undesirable reactions of the gearfto the primemover because on each shaft or axle two centrifugal weights areoppositely moved. Between the centrifugal weights of a shaft oraxletlfere is a balancingin that sense that one weight receives energywhile the other givesout nergy} J1. Q

The gear according to my'inventi'onworks also as a coupling as soon asdrive speed anddriv'en torque have reached certain values;In'thisca'se', the gear establishesdirect connection between drive shaftand driven shaft. The centrifugal forces of all centrifugal weightsexert torques on the crank and the return crank in the same direction,namely in the clockwise direction. For the sum of all'c'entrifugalforces there is :a dis. tinct position of the centrifugal'weights andthe crank, where the torque exertedon the crankqis a maximum. If thistorque cannot beiovercome by the load torque, coupling takesplace. Theload torque is not able to force the centrifugal weights back and forthis reason the: whole gear must rotate together with the drive shaft,at the same speed. Moreover; the *gear; works 388 an Fluctuations }ofthe input torque are absorbed byvariations of kinetic energy of thecentrifugal weights and can thus not reach the driving shaft. Variationsof the load torque result in'changes in positionofthe centrifugalweights with regard to the aXiSIIWhIiCh they approach when the loadtorque is increased. On a further increase of the load torque, themaxi-. mum torque of all centrifugal weights'will finally be exceeded sothat the gear will slip, while the average value of the torque remainsunchanged.

The torque fluctuates periodically about this average value. '4 Theinstantaneous torque exerted by eachcentrifugalweightis increased justas much as it is decreased in the next phase. The excess powercorresponding to the difference of the inputspeed from the output speedreturns into the-prime mover and accelerates it while the driven shaftis being retarded. In this way conditions'will soon be reached, at whichthe coaster brake locks and increases the drive torque. suitabledimensions being provided, slip does, not occur before the driven shafthas reached a speed which is smaller-than the speed at whlchcouplingtakes place, i. e'., at which slip disappears. ,This fact isvverydesirable for-use of my gear in .v e hicle's If the crank is heldfast to-be at rest, the whole power. returns to theprime mover at a verygreat torque exerted. on the crank. 2 g a Referring now to Fig. 11, thecentrifugalweight f is replaced by two weights is and f6. The weight 15represents the mass of the rack 2 etc. It exerts a smaller centrifugalforce thanthe weight is. The point of application of the centrifugalforce exerted by the weight is lies in the axis of 0. As a rule theweight f6 does not take part in the oscillations of the lever cc' and isthus not pressed inwardly and, therefore, does not exert a correspondingforce. The weights is and fa are rigidly connected with each other andare linked to the arm 0 as at L.

The weight 5 takes part in the oscillations of aooaerr- 7; theiarmzcf.When the angular velocity of: the toothedwheeliis-niL'that is, whenthe-coaster brakelocks; alsojs isforced inwardly since c-c' is gfurther;rotatedin the counterclockwise, direciomand fc-, exer.ts-a force on thecrank it by means of: the parts c '--c-d. When the Weight is isswungoutagain, it;forces the weight is inwardly andiholds the coasterbrake further in looking condition-by; means of the rack 2. Weight is isfurther supported on the coaster brake, exerts further atorqueon thecrank it and returns withoutshocks intozthe rest position shown in Fig.11.

Thezweight fsis. chosen .in such a manner that the centrifugalforceapplied to it may effectthe above-mentioneddirect coupling of shafta with shaft b as soon as a certain drive speed and-acertain load torqueoccur.

- 'My 'g ear is especiallywell suited for vehicles driven by internalcombustion engines because it:is automatically and infinitely variablyadapted tothe. load torque, since the latter furnishes-the force for:forcing the centrifugal weights back.- My'gear likewise variesautomatically and infinitely independence on the drive speed for'thereason that the centrifugal weights rotate at this speed so'that theforce necessary for balancing theload torquedepends on the drive speed.The transmission ratio automatically adjusted by the gear depends on thedrive speed and the load torque.

When the cage-s1, s2, 53 (Fig. 3)' moves at'a lower speed than thecrank, that is, when the vehicle pushes, the coaster brake will alsolook, butduring the other half of a revolution, and will drive-the cage.From this it follows that the prime mover may also act as a brake.-

WhileI have described and illustrated difierent embodiments of myinvention, I do not wish to unnecessarily" limit the scope of thisinvention, but'reservethe right to make such modifications andrearrangement of the several parts as may come within the purview of theaccompanying claims:

rclaimz 1. In an infinitely variable gear, a shaft, a crankshaft,rocking members with their axes of oscillation eccentrical to the axisof said shaft and arranged to rotate together with the firstmentionedshaft at the same speed, centrifugal weights linked to said rockingmembers, pivoting means rigidly connected with said centrifugal weights,link means connecting said rocking members wlth said crankshaft, alocking mechanism comprisinga wheel, and coupling means linked on saidpivoting means and coupled with said wheel to act on the latter.

2. In an infinitely variable gear according to claim, 1, a transmissiongear arranged to increase the oscillations transmitted to said wheel bysaid coupling means.

3C In an infinitely variable gear according to claim 1, some, of saidrocking members forming double-armed levers, some others single-armedlevers.

7 '4. In an infinitely variable gear according to claim 1, some of' saidrocking membersforming double-armed. levers. some others. singlesarmcd.1evers,..saidv rocking members beingv arranged in,

pivotablepairs, each comprising a doublerarmed lever and asinglerarmedlever.

5,. In an, infinitely variable gear according to claim 1, some ofsaidrocking members forming double-armed levers, some otherssingle-armed levers, eachof. said double-armed levers, being pivotableabout a center close to, the pivoting center of one ofvsaidsingle-armedlevers 6. In an infinitely variable gear. according; toclaim 1, two at a time of said centrifugal weights being arrangedsymmetrically with, regard to, the axisof rotation ofsald shaft.

7. Imam-infinitely variablegear accordingto claimLguidesrotatable aroundtheaxis ofroltation ofl said shaft, said coupling means. forming racksmovably guidedin said uides...

8. In. an infinitely variable, gear, according to claim 1, a. memberrotatable around. theaxis of rotation offlsaid shaft, comprising twoguides symmetrically arrangedwith regard to theaxisof rotation of saidmember, said coupling means forming racks guided in said guides.

9. In aninfinitely variable gear according to claim- 1, said centrifugalweights being able to exert by their centrifugal force alone a tomueonsaid crankshaft by the intermediary of said rockingmembers and said linkmeans.

10. In an infinitely variable gear according to claim 1, the effectofjeachofsaidcentrifugal weights; correspondingto the efiect of two oenstrifugal weights, one-of which carries out noescillationinthe; caseofdirect couplin whilethe other furnishes,thecentriiugal force necessaryfor couplin 11. Inan, infinitely variable gear, a-shaft, reciprocatingmeans, rocking members with their axes of, oscillation eccentrical tothe axis of aid shaft, and arranged to rotate together with thefirst-mentionedshaft at the same speed, cene trifugal weights linked tosaid rocking members, pivoting means rigidly connected'withsaidcentrifugal weights, link means connecting said rockingmembers with saidreciprocating means, a locking mechanism comprising a wheel, andcoupling means linked onsaid'pi-voting means and coupled with saidwheel, to act on thelatter,

WALTER ZWICK REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date- 1,276,168 Buchholz Aug, 20, 19181;542,668 Constantinesco June 16, 1925 1,718,092, Turner June 18, 19291,798,723 Chalmers Mar. 31, 1931 2,144,609 Barber g Jan. 24, 1939FOREIGN PATENTS Number Country Date 724,757 France g ..r- May 2 i932

